I've been trying this on and off for a couple of years, blocking out time in my day to do "actual work" and avoiding meetings. All that happens is the sales people (inevitably it is sales people) book a meeting with a customer without checking my calendar first.
Or set up a rotation with a few other coworkers so that _someone_ can always take a sales call and pass it off to them if it’s during your off/focus day and vice versa for theirs.
